Abrasive suspension jet cutting system having reduced system wear and process materials reclamation

ABSTRACT

An abrasive suspension jet cutting system, the system includes a cutting head. The cutting head has a feed assembly, nozzle and acceleration cavity therebetween. The feed assembly has a slurry orifice and a shielding fluid orifice. Within the acceleration cavity abrasive slurry and shielding fluid are accelerated together from the slurry orifice to the nozzle while maintaining a shielding fluid barrier substantially unmixed with the abrasive slurry around the abrasive slurry. The cutting head is further configured to have both the slurry and shielding fluid pass substantially unmixed through the nozzle thereby limiting nozzle wear. A wear control system is provided to reduce wear of the nozzle and other system components during start and stop. The system may further include a reclamation system that collects and reclaims used abrasive particles and fluid and returns them back to the cutting head to be reused thereby reducing system operational costs.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority of U.S. Provisional Patent Application No. 62/939,868 filed Nov. 25, 2019 and U.S. Provisional Patent Application No. 63/040,823 filed Jun. 18, 2020, both of which are herein incorporated by reference.

FIELD

The present invention generally relates to abrasive jet cutting. More specifically, the invention relates to an abrasive suspension jet cutting system having reduced cutting head and system component wear, and process materials reclamation system.

BACKGROUND

The conventional method of cutting with abrasive is to create an abrasive jet by injecting a very-high-velocity water jet (pressurized from 20-90 kpsi and traveling at up to 1,200 m/s) into a chamber where abrasive grit has been blown by compressed air, transferred using a vacuum, or introduced via the Venturi effect. The water, air and abrasive flows are mixed in a refractory-material tube and then ejected through a small opening to create an abrasive jet for cutting. Because the transfer of energy from the water jet to the particles is very inefficient, much of the energy put into the system is wasted through breaking up particles, wearing away at the focusing tube and generating excess heat that does not go into cutting. Typically, the resulting jet is about 1 mm in diameter with an output velocity of only about 350 m/s losing about 80% of the originally introduced energy. This type of abrasive jet cutter is called an Abrasive Water Jet (AWJ) cutter and is used worldwide. Although not very efficient, the AWJ system is used because of its ability to cut almost any material with great detail and without heat, and its general simplicity to understand and operate.

Another type of abrasive jet cutting system is an Abrasive Suspension Jet (ASJ) cutter. Rather than mixing grit and water after the very-high-velocity water jet is formed, as in an AWJ, the grit is instead mixed with water at ambient pressure to form the abrasive suspension. The abrasive suspension is then pumped up to very-high pressure (e.g. 30 kpsi) to form a suspension jet having a very high velocity (e.g. 650 m/s) and a diameter of about 0.5 mm. Alternatively, an ASJ can be formed by diverting all or a portion of the high pressure liquid flow through an abrasive filled chamber where particles are entrained into the flow, forming the abrasive suspension that is delivered to the cutting jet. Because of the higher velocity and no air in the cutting jet, ASJ cuts much faster than the AWJ does. The ASJ has been known for decades to be a more efficient form of abrasive jet generation, but has been used very little because the abrasive slurry jet erodes the jet nozzle so quickly that it is not practical. The complexity of pumping and controlling the flow of an abrasive slurry at high pressure and velocity has further limited the technology's reach due to rapid wear of all system components (pumps, valves, fittings, tubing) that contact the abrasive slurry.

Attempts have been made to improve the ASJ cutter and try to minimize some of the above noted problems. For example to reduce abrasive wear on system components, U.S. Pat. No. 4,707,952 to Krasnoff proposes the use of two fluid streams. One fluid stream is to provide concentrated slurry at low velocity so as to cause minimal component erosion and the other fluid stream provides an accelerating fluid to create the high velocity jet. Due to excessive mixing during acceleration, the Krasnoff system does not adequately protect the nozzle from wear. To improve upon Krasnoff, U.S. Pat. Nos. 8,251,773, 8,591,290, 8,491,355 and 8,834,232 to Liwszyc et al. propose a system to more reliably control the delivery of abrasive slurry to a cutting nozzle. Liwsyzc does this by introducing two independently operable energizing means to control the two fluid streams independently. One of the energizing means starts and stops the flow of slurry prior to operating any valves in the slurry flow path which would otherwise be subject to extreme wear. The second energizing means moves the second drive fluid to maintain system pressure. However, the increased cost and complexity of that system combined with the lack of an effective solution to nozzle wear have limited its adoption.

Another issue with abrasive jet cutting systems in general lies in the cost associated with abrasive particle usage. Abrasive particles make up approximately 50% of the operating costs of an AWJ system and are typically discarded after only one use, adding an additional cost of disposal. The currently available reclamations systems for AWJ are expensive to purchase and operate due to the high energy costs of drying the used abrasive particles making them economically viable in only a small number of shops. ASJ systems have even higher abrasive costs as they typically consume even larger amounts of abrasive than AWJ systems and there are no commercially available abrasive recycling systems.

In general, the use of AWJ systems has been limited by their inefficiency and high abrasive costs, and the use of ASJ has been limited by their complexity, high nozzle and other system component wear rates as well as high abrasive costs.

Given what presently is available for abrasive jet cutting systems, it is clear that there is still opportunity to improve nozzle and system component wear, and minimize costs associated with abrasive particle usage. The main objective of the present invention is therefore to provide an ASJ system that both improves nozzle and system component wear, and reduces operational costs by providing an abrasive particle reclamation system.

SUMMARY

In one implementation, the present disclosure is directed to a system for abrasive suspension jet cutting using an abrasive slurry and shielding fluid. The system comprises a feed assembly having a slurry orifice and a shielding fluid orifice, a nozzle, and an acceleration cavity between the feed assembly and the nozzle. Within the acceleration cavity the abrasive slurry and shielding fluid are accelerated together from the slurry orifice to the nozzle while maintaining a shielding fluid barrier substantially unmixed within abrasive slurry around the abrasive slurry. Both the slurry and shielding fluid further pass substantially unmixed through the nozzle.

In another implementation, the present disclosure is directed to a system for abrasive suspension jet cutting using abrasive slurry having abrasive particles contained within a fluid. The system comprises a cutting head having a nozzle to eject a jet of slurry at high speed. The system further comprises a reclamation system that collects used abrasive particles and fluid and then returns reclaimed abrasive particles and fluid to the cutting head.

In another implementation, the present disclosure is directed to a reclamation system having a feed assembly. The reclamation system comprises a collection system to collect slurry and shielding fluid, a separator to separate out reusable abrasive particles from used slurry and shielding fluid to produce reclaimed slurry and reclaimed shielding fluid. The reclamation system further has a recirculation system to reintroduce the reclaimed slurry and the reclaimed shielding fluid to the feed assembly.

In another implementation, the present disclosure is directed to a reclamation system having a separator system. The separator system includes a filter housing having a dilute slurry inlet, a first shielding fluid outlet, a second shielding fluid outlet, a concentrated slurry outlet, a stationary filter, a movable filter and movable shuttle puck. The stationary filter is located between the dilute slurry inlet and the second shielding fluid outlet. The movable filter is between the dilute slurry inlet and the first shielding fluid outlet. The movable filter and movable shuttle puck can move together to act as plunger and can move independently to back-purge the movable filter.

In yet another implementation, the present disclosure is directed to an abrasive wear control system for regulating movement of pressurized abrasive slurry and shielding fluid through a suspension jet cutting head. The system comprises a slurry to shielding fluid volume flow regulator and a valve system that is operable to provide reverse flow of abrasive slurry through the cutting head while maintaining positive shielding fluid flow during stopping to reduce nozzle wear. When starting the suspension jet cutting head, the slurry to shielding fluid volume flow regulator establishes a jet of shielding fluid prior to starting the flow of slurry to the cutting head in order to minimize slurry mixing with the shielding fluid when starting slurry flow. When stopping the suspension jet cutting head, the slurry to shielding fluid volume flow regulator stops the flow of slurry to the cutting head, the vent valve is opened temporarily allowing shielding fluid to flow in in reverse from the cutting head and through the slurry valve prior to closing the slurry valve and vent valve in order to minimize nozzle wear during nozzle depressurization.

In yet another implementation, the present disclosure is directed to a method of reducing abrasive wear of a suspension jet cutting head nozzle. The method comprises providing a cutting head with a nozzle, a slurry to shielding fluid volume control flow regulator, a slurry valve and a slurry vent valve. The method then involves energizing the shielding fluid and slurry. The method then involves reversing flow of the abrasive slurry through the nozzle while maintaining positive shielding fluid flow during stopping operation to reduce nozzle wear.

In yet another implementation, the present disclosure is directed to a method of reducing abrasive wear of a suspension jet cutting head nozzle. The method comprises providing a cutting head with a nozzle, a slurry to shielding fluid volume control flow regulator, a slurry valve and a vent valve. The method then involves energizing the shielding fluid and slurry. The method then involves starting flow of abrasive slurry through the nozzle only after shielding fluid is flowing through the nozzle at pressure during starting operation to reduce nozzle wear.

In still yet another implementation, the present disclosure is directed to a cutting head for abrasive suspension jet cutting using an abrasive slurry and a shielding fluid. The cutting head comprises a feed assembly having a slurry orifice and a shielding fluid orifice. The cutting head further has a nozzle having a nozzle entrance orifice, a nozzle exit orifice and a nozzle orifice length therebetween. The cutting head still further has an acceleration cavity between the slurry orifice and the nozzle entrance orifice, the acceleration cavity narrows from the slurry orifice to the nozzle orifice to provide hydrodynamic focusing within the acceleration cavity. Within the acceleration cavity the abrasive slurry and shielding fluid are accelerated together from the slurry orifice to the nozzle entrance orifice while maintaining a shielding fluid barrier substantially unmixed with abrasive slurry around the abrasive slurry, both the slurry and shielding fluid pass substantially unmixed through the nozzle.

In still yet another implementation, the present disclosure is directed to a system for abrasive suspension jet cutting. The system comprises a feed assembly having a slurry orifice and a shielding fluid orifice, a nozzle, and an acceleration cavity between the slurry orifice and nozzle. The system further comprises abrasive slurry and shielding fluid where the abrasive slurry and shielding fluid have the same flow characteristics. Within the acceleration cavity the abrasive slurry and shielding fluid are accelerated together from the slurry orifice to the nozzle as both pass through the acceleration cavity and exit the nozzle.

BRIEF DESCRIPTION OF DRAWINGS

For the purposes of illustrating the invention, the drawings show aspects of one or more embodiments of the invention. However, it should be understood that the present invention is not limited to the precise arrangements and instrumentalities shown in the drawings, wherein:

FIG. 1 is perspective view of one embodiment of a system for abrasive suspension jet cutting system in accordance with the present invention;

FIG. 2 is an enlarged view of the dashed outline in FIG. 1 of the abrasive suspension jet cutting system highlighting the cutting head;

FIG. 3 is a sectional view along line 3-3 of the cutting head of the abrasive suspension jet cutting system of FIG. 2;

FIG. 4 is a sectional view of the cutting head and enlarged sectional views of the jet forming element and nozzle of the abrasive suspension jet cutting system of FIG. 1;

FIG. 5 is a schematic showing one embodiment of a fluid delivery system for the abrasive suspension jet cutting system of FIG. 1;

FIG. 6 is a schematic showing another embodiment of a fluid delivery system for the abrasive suspension jet cutting system of FIG. 1 without a fluid buffer tank;

FIG. 7 is a schematic showing another embodiment of a fluid delivery system for the abrasive suspension jet cutting system of FIG. 1 that works using a batch of prepared slurry;

FIG. 8 is a schematic showing an electronic control system used in conjunction with the abrasive suspension jet cutting system of FIG. 1;

FIG. 9 is a sectional view showing schematically the formation of the cutting jet within the cutting head of the abrasive suspension jet cutting system of FIG. 1;

FIG. 10a is a sectional view showing schematically the details of abrasive particle and shielding fluid interaction within a cutting head that result from long distances and low angles within an acceleration cavity;

FIG. 10b is a sectional view showing schematically the details of abrasive particle and shielding fluid interaction within a cutting head that result from short distances and high angles within the acceleration cavity of the abrasive suspension jet cutting system of FIG. 1;

FIG. 11a is a sectional view showing schematically the details of abrasive particle and shielding fluid interaction within a cutting head that result from a long nozzle orifice length;

FIG. 11b is a sectional view showing schematically the details of abrasive particle and shielding fluid interaction within the cutting head of the abrasive suspension jet cutting system of FIG. 1 that has a short nozzle orifice length;

FIG. 12a is a sectional view showing schematically the details of abrasive particle and shielding fluid interaction within a cutting head that result from low slurry to shielding fluid volume percentage;

FIG. 12b is a sectional view showing schematically the details of abrasive particle and shielding fluid interaction within a cutting head that result from high slurry to shielding fluid volume percentage;

FIG. 12c is a sectional view showing schematically the details of abrasive particle and shielding fluid interaction within a cutting head that result from optimal slurry to shielding fluid volume percentage of the abrasive suspension jet cutting system of FIG. 1;

FIG. 13 is a schematic showing one embodiment of an abrasive wear control system used in conjunction with the suspension jet cutting system of FIG. 1;

FIG. 14a is a schematic showing a first step of the fluids flow for the startup procedure of the wear control system used in conjunction with the suspension jet cutting system of FIG. 1;

FIG. 14b is a schematic showing a second step of the fluids flow for the startup procedure of the wear control system used in conjunction with the suspension jet cutting system of FIG. 1;

FIG. 14c is a schematic showing a third step of the fluids flow for the startup procedure of the wear control system used in conjunction with the suspension jet cutting system of FIG. 1;

FIG. 15a is a schematic showing a first step of the fluids flow for the shutdown procedure of the wear control system used in conjunction with the suspension jet cutting system of FIG. 1;

FIG. 15b is a schematic showing a second step of the fluids flow for the shutdown procedure of the wear control system used in conjunction with the suspension jet cutting system of FIG. 1;

FIG. 15c is a schematic showing a third step of the fluids flow for the shutdown procedure of the wear control system used in conjunction with the suspension jet cutting system of FIG. 1;

FIG. 15d is a schematic showing a fourth step of the fluids flow for the shutdown procedure of the wear control system used in conjunction with the suspension jet cutting system of FIG. 1;

FIG. 15e is a schematic showing a fifth step of the fluids flow for the shutdown procedure of the wear control system used in conjunction with the suspension jet cutting system of FIG. 1;

FIG. 15f is a schematic showing a sixth step of the fluids flow for the shutdown procedure of the wear control system used in conjunction with the suspension jet cutting system of FIG. 1;

FIG. 16 is a schematic showing the abrasive suspension jet cutting system of FIG. 1 including details of the abrasive particle and fluid reclamation system;

FIG. 17 is a schematic showing a single filter separation system that may be used in conjunction with the abrasive particle and fluid reclamation system of FIG. 16;

FIG. 18 is sectional view showing the details of one embodiment of a single filter separator that may be used with the single filter separation system of FIG. 17;

FIG. 19 is a schematic showing a dual filter separation system that may be used in conjunction with the abrasive particle and fluid reclamation system of FIG. 16;

FIG. 20 is sectional view showing the details of one embodiment of a dual filter separator that may be used with the dual filter separation system of FIG. 19;

FIG. 21 is a schematic showing a plunger separation system that may be used in conjunction with the abrasive particle and fluid reclamation system of FIG. 16;

FIG. 22 is a schematic showing a dual filter separation system with a shuttle puck that may be used in conjunction with the abrasive particle and fluid reclamation system of FIG. 16; and

FIG. 23 is a sectional view showing the details of one embodiment of the filter housing used with the dual filter separation system with a shuttle puck of FIG. 22.

DETAILED DESCRIPTION

An abrasive suspension jet cutting system 30 for cutting a part 32 is illustrated in FIGS. 1-23. Cutting system 30 comprises a cutting head 34. Cutting head 34 includes a feed assembly 36 having a slurry orifice 38 and a shielding fluid orifice 40. Cutting head 34 further includes acceleration cavity 42 and nozzle 44. Acceleration cavity 42 is located between feed assembly 36 and nozzle 44. Acceleration cavity 42 is configured so that abrasive slurry 60 and shielding fluid 62 are accelerated together from slurry orifice 38 to nozzle 44 while maintaining a shielding fluid barrier substantially unmixed with the abrasive slurry around the abrasive slurry. Cutting head 34 is further configured so that both slurry 60 and shielding fluid 62 continue to pass substantially unmixed through nozzle 44 and exit the nozzle exit orifice 41 as a high velocity cutting jet 45.

FIGS. 1 and 2 show the overall abrasive suspension jet cutting system 30. In addition to cutting head 34, abrasive suspension jet cutting system 30 further comprises cutting table 50 with platform 52 that supports part 32 to be cut. Cutting table 50 has a positioning arm 56 that supports and moves cutting head 34 above part 32. Cutting system 30 further comprises a fluid delivery system 94 (94 a, 94 b, 94 c) that provides slurry 60 through slurry supply line 61 and shielding fluid 62 through supply lines 64 (64 a and 64 b) to cutting head 34. Electronic control system 66 with a user interface 68 is used to operate abrasive suspension jet system 30. Cutting system 30 may also include an abrasive particle and fluid reclamation system 100 for reclaiming the abrasive particles 72 and fluid needed to operate the cutting system.

The components of cutting head 34 are shown in more detail in FIG. 3. Cutting head 34 is generally formed along a central cutting axis A. Cutting axis A is the axis along which the cutting jet 45 is formed. The body of cutting head 34 includes a central core 78 where the slurry and shielding fluid are prepared for injection through the feed assembly 36 and into acceleration cavity 42. Slurry supply line 61 supplies slurry to central slurry tube 80 that resides within central core 78. One or more shielding fluid supply lines, such as 64 a and 64 b, supply shielding fluid to shielding fluid cavity 82 that resides within central core 78. Shielding fluid cavity 82 is an annular cavity that surrounds central slurry tube 80. Central core 78 may include one or more flow conditioning elements 84 that may be turbulence-reducing screens and swirl reducing elements to ensure uniform velocity fluid flow to feed assembly 36. At the end of slurry tube 80 is slurry orifice 38. At the end of shielding fluid cavity 82 is shielding fluid orifice 40.

At the end of central core 78 of cutting head 34 is jet forming element 86, FIG. 4. Jet forming element 86 is preferably a removable element that can be secured in to cutting head 34. Jet forming element 86 includes jet forming insert 88 and jet forming insert holder 90. Jet forming insert 88 is preferably press-fit into jet forming insert holder 90. Jet forming element 86 may have a seal 92 sealing with the rest of the cutting head body. Within jet forming insert 88 lies feed assembly 36, acceleration cavity 42 and nozzle 44. Nozzle 44 has a nozzle entrance orifice 43, a nozzle exit orifice 41 and a nozzle orifice length 39. Nozzle 44 includes a nozzle length 39 and nozzle orifice diameter 37, wherein the nozzle length is less than the nozzle orifice diameter. Acceleration cavity 42 narrows from slurry orifice 38 to the nozzle entrance orifice 43 to provide hydrodynamic focusing.

Supplying abrasive slurry 60 and shielding fluid 62 to cutting head 34 is fluid delivery system 94 (94 a, 94 b, 94 c). Generally fluid delivery system 94 has a fluid energizing means 96, an abrasive slurry supply, a shielding fluid supply and a combination of valves to drive and regulate both abrasive slurry and shielding fluid through cutting system 30. Fluid delivery system 94 may include abrasive wear control system 98, which is a set of regulators and valves to reduce system wear. Fluid delivery system 94 may include an abrasive particle and fluid reclamation system 100.

More specifically in one embodiment, FIG. 5, fluid deliver system 94 is a continuous operation fluid delivery system 94 a that includes two slurry cylinders 102 (102 a and 102 b) as well as two buffer tanks, slurry buffer tank 104 and shielding fluid buffer tank 106. Each slurry cylinder 102 (102 a and 102 b) further has a fill valve 108 (108 a and 108 b) and an isolation valve 110 (110 a and 110 b). Isolation valve 110 is closed as slurry 60 is pumped into each cylinder and opened when delivering slurry to cutting head 34. A single pump/energizing means 96 is used to commonly energize both abrasive slurry 60 and shielding fluid 62 and move both fluids through acceleration cavity 42 and out nozzle 44. Energized slurry flowing out of slurry cylinders 102 is regulated by slurry drive valves 111 (111 a and 111 b). An additional slurry valve 113 is included to control slurry delivery to cutting head 34.

In another embodiment, FIG. 6, simplified continuous operation fluid delivery system 94 b is a continuous system without buffer tanks, but contains all other elements of fluid delivery system 94 a. This embodiment reduces the footprint of the system and increases simplification of fluid delivery system 94 b.

In another embodiment, FIG. 7, fluid delivery system 94 c is a batch system. In this batch system only one slurry cylinder 102 is used and cutting head 34 must be turned off when refilling the slurry supply.

Abrasive suspension jet cutting system 30 further includes electronic control system 112, FIG. 8. Electronic components are contained within an electronics enclosure 116. Electronic components include a computer 118, programmable logic controller 120, data acquisition/logging device 122 and a multi-axis motion control system 124 that drives multi-axis motion hardware 125. A user interface 68 allows an operator to interface with electronic components and control cutting system 30. Electronic control system 112 regulates fluid delivery system 94 which may include wear control system 98 and reclamation system 100. Electronic control system 112 further controls the multi-axis motion control system 124 that drives positioning arm 56.

Formation of a cutting jet 45 within cutting head 34 occurs as shown in FIG. 9. Shielding fluid 62 is pumped through shielding fluid cavity 82. Shielding fluid 62 enters acceleration cavity 42 as an annulus of shielding fluid 62 from shielding fluid orifice 40 and fills the acceleration cavity. Once acceleration cavity 42 is full of shielding fluid 62 flowing at working pressure, slurry 60 is then introduced into the acceleration cavity 42. Because acceleration cavity 42 narrows from slurry orifice 38 to nozzle 44, the resulting fluid flow is a cone of slurry 60 surrounded by an annular cone of shielding fluid 62 with the slurry and shielding fluid accelerating together from feed assembly to the nozzle. Slurry 60 surrounded by shielding fluid 62 then pass through nozzle 44 and out the nozzle exit orifice 41 as cutting jet 45.

The pressure gradient within the acceleration cavity 42 has the potential to cause mixing between the slurry having abrasive particles and shielding fluids if the two fluids do not flow in a similar manner when exposed to this pressure gradient resulting in increased nozzle wear. For this reason, it is critical for the slurry and shielding fluid to have similar rheologic parameters including viscosity and the strain rate dependence of this viscosity. A variation in these parameters between the two fluids will cause a local variation in the Reynolds number along the boundary between the two fluids resulting in the development of a shear force that can induce mixing of abrasive slurry and shielding fluid. To minimize this mixing the present invention uses the same base fluid for the shielding fluid and slurry. The base fluid may be one from the group including water, water and a suspension agent, oil, and oil and a suspension agent. A modifying additive may be added to the slurry and shielding fluids to give them similar flow characteristics, including viscosity and viscosity shear rate dependence, and ensure equivalent acceleration without mixing in the acceleration cavity 42 and through the nozzle exit orifice 41. This additive may be a xanthan gum, guar gum, cellulose derivatives, polyacrylamide, gelatin, bentonite, another natural synthetic polymer or clay.

Turning to FIGS. 10a and 10b , the longer the acceleration cavity 42, the more time slurry 60 and shielding fluid 62 spends within the acceleration cavity to intermingle and mix. Hence a long acceleration cavity results in increased mixing of abrasive particles and shielding fluid. With abrasive particles in the shielding fluid, as the shielding fluid passes through nozzle 44, there is nozzle wear. The mixing is due to differences in viscosity as discussed above and the effect of any turbulence to be increased with time. Hence it is critical to have a short acceleration cavity with a taper angle θ of 15-degrees or more that provides minimum interaction between the abrasive particles and shielding fluid, which is critical to reduce nozzle wear.

It has also been determined that nozzle orifice length 39 effects mixing of abrasive slurry 60 and shielding fluid 62 within nozzle 44, FIGS. 11a and 11b . An abrasive particle within slurry 60 may follow a trajectory shown by bold line (trajectory T) in FIG. 11a . This trajectory is a result of the momentum of the abrasive particle. As abrasive particle 72 enters nozzle 44, the particle wants to continue on generally the same path that the particle followed through the lower part of acceleration cavity where the velocity is high. This means particle 72 wants to move into the shielding fluid 62. At a distance D, some of the abrasive particles will start to move into the outer region of the shielding fluid and to impinge upon the wall of nozzle 44 and start to wear the surface of the nozzle away. Over time, this will degrade nozzle 44 by opening the nozzle up and changing the nozzle's shape. To eliminate this problem, it is critical that nozzle orifice length should be made as short as possible. FIG. 11b shows where when nozzle orifice length 39 is shortened to less than D, the abrasive particles will no longer make contact with the nozzle wall. An optimum nozzle orifice length is generally when the nozzle orifice length 39 is shorter than the diameter of nozzle entrance orifice 43.

It has also been determined that slurry to shielding fluid volume ratio effects mixing, FIGS. 12a-12c . For low slurry volume, FIG. 12a , the trajectory of an abrasive particle 72 is such that the particle may move into shielding fluid 62 and contact nozzle 44 abrading the nozzle wall before the particle has exited the nozzle. For high slurry volume, FIG. 12b , the trajectory of an abrasive particle 72 is such that the particle may also move into shielding fluid 62 and contact nozzle 44 abrading the nozzle wall before the particle has exited the nozzle. FIG. 12c illustrates an optimal slurry to shielding fluid volume allowing abrasive particles to exit nozzle 44 before the particles have a chance to abrade the nozzle wall. For optimal operation and reduced wear the abrasive slurry has an abrasive slurry volume, the shielding fluid has a shielding fluid volume, the abrasive slurry volume and shielding fluid volume define a total volume, and the system provides that the abrasive slurry volume may be greater than 30-percent of the total volume as the abrasive slurry exits the nozzle. The large slurry volume percentage allows for increased abrasive jet power and cutting efficiency while maintaining nozzle protection and is made possible by the cutting head and operational details disclosed herein.

To further eliminate abrasive wear of nozzle 44 of cutting head 34, an abrasive wear control system 98 may be incorporated into fluid delivery system 94, FIG. 13. Abrasive wear control system 98 incudes a slurry to shielding fluid volume regulator 126 and a valve system 128. Valve system 128 includes a slurry valve 113 and a slurry vent valve 132. Abrasive wear control system 98 is important during the formation and shutdown of cutting jet 45. Abrasive wear control system 98 works to minimize mixing of abrasive particles 72 into shielding fluid 62 and thus mitigate further wear on the cutting head components.

FIGS. 14a-c illustrate how abrasive wear control system 98 operates during the startup procedure. In FIG. 14a , no shielding fluid 62 is running through cutting head 34. Flow of shielding fluid 62 is then initiated to provide clean shielding fluid at pressure within acceleration cavity 42 and nozzle 44, FIG. 14b . Slurry valve 113 is then opened and slurry 60 introduced into the shielding fluid 62 that is already flowing through acceleration cavity 42, FIG. 14c . In this manner, slurry 60 mixing with shielding fluid 62 is minimized because the slurry is not introduced into acceleration cavity 42 when transient, nonlinear flow of shielding fluid is occurring at the beginning of shielding fluid flowing into the acceleration cavity.

FIGS. 15a-f illustrate how abrasive wear control system 98 operates during the shutdown procedure. In FIG. 15a , slurry 60 with a clear shielding fluid layer is flowing through acceleration cavity 42 and out nozzle 44. Slurry valve 113 is shut off so that all slurry 60 is cleared from acceleration cavity 42 and nozzle 44, FIG. 15b . Vent valve 132 (132 a and 132 b) and slurry valve 113 are then opened to flush all slurry through cutting head 34, through slurry valve 113 and out vent valve 132, FIGS. 15c and 15d . Vent valve 132 and slurry valve 113 are then shut off, FIG. 15e . Finally, the slurry to shielding fluid volume flow regulator 126 is shut off to stop all fluids flowing through cutting head 34, FIG. 15f . Slurry to shielding fluid volume flow regulator may include a slurry pressure regulator and a shielding fluid pressure regulator. The slurry to shielding fluid volume flow regulator may be a shielding fluid flow control valve. Shielding fluid volume flow regulator 126 and the rest of the valve system may allow reverse flow of abrasive slurry through the cutting head to reduce nozzle wear.

In previous ASJ systems, the starting and stopping of the slurry flow requires the operation of a valve or valves on the abrasive slurry, which leads to significant wear of the internal valve components. The present invention alleviates this wear by purging abrasive from any valve located in the slurry flow path with clean shielding fluid before operating the valve. This allows for the frequent starting and stopping of jet 45, which is required during typical operation, without producing significant valve wear.

Abrasive suspension jet cutting system 30, FIG. 16, may include an abrasive particle and fluid reclamation system 100 (a.k.a. reclamation system, abrasive slurry reclamation system) to reduce costs of abrasive particle 72 and shielding fluid 62. Reclamation system 100 includes jet catch tank 134, which in combination with catch tank agitator 136 creates collection system 135. Reclamation system 100 also includes a separator system 160, where separator system 160 may be any of the separator systems 160 a, 160 b 160 c and 160 d. Abrasive particles 72 and shielding fluid 62 are collected in jet catch tank 134 after being in jet 45 to cut a part 32. At this point the fluid is a used fluid that is a mixture of slurry 60 and shielding fluid 62. The used fluid has a single base fluid of uniform chemical composition and is used to create both slurry and shielding fluid. Catch tank agitator 136 may be included within catch tank 134 to help keep abrasive particles 72 suspended and uniformly mixed. Used fluid and particles from catch tank 134 are delivered to a course overflow strainer 137 to filter out any large particles. The fluid is then moved to an overflow tank 138. Used fluid from the overflow tank is then pumped by dilute slurry pump 142 from overflow tank 138, through degasser 144 and into separator system 160. Separator system 160 contains separator 146 (146 a, 146 b, 146 c and 146 d), fluid flow meter 195, and fluid properties controller 152. Within separator system 160, reusable abrasive particles 72 and a portion of the base fluid are separated from used fluid to produce reclaimed slurry and reclaimed shielding fluid. Separator 146 may be a settling tank, hydrocyclone, centrifuge, mechanical filter, tangential flow filter, or a combination thereof. Reclaimed shielding fluid is then pumped by shielding fluid boost pump 148 through a fines filter 150 to remove waste particles from shielding fluid. Clean, reclaimed shielding fluid is then returned through fluid delivery system 94 to be reused by cutting head 34 to form cutting jet 45. Separated abrasive particles suspended in fluid as a concentrated slurry is processed through fluid property controller 152. In fluid property controller 152, the fluid properties of density or viscosity may be measured by fluid property sensor 153 and processed by density logic 155 or viscosity logic 157. The density information generated by density logic 155 is used to concentrate or dilute the slurry being processed in separator 146. The viscosity information generated by viscosity logic 157 is used to monitor the relative changes in fluid viscosity over time. When sufficiently large changes in viscosity have occurred, viscosity logic 157 will indicate that the fluid's viscosity needs to be adjusted, which may include adding polymer concentrate 145 to jet catch tank 134. Separated and reclaimed slurry is then transferred by slurry boost pump 156 and returned by fluid delivery system 94 as slurry 60 to cutting head 34 to form cutting jet 45. Fluid flow meter 195 may be installed on the dilute slurry inlet 192, the reclaimed shielding fluid outlet(s) 194 a 194 b or both. Together dilute slurry pump 142, separator system 160, slurry boost pump 156, shielding fluid boost pump 148 and associated valves create a recirculation system. Reclamation system 100 further may further include a conditioner system to maintain rheological and biological properties of the base fluid. Rheological properties may include viscosity and shear thinning rate. Conditioner system may include a biocide system. Rheological test system includes a rheological test system and a rheological modifier system. Associated with these systems are polymer concentrate 145 and slurry concentrate 147 that are available to adjust viscosity and slurry density.

The purpose of separator system 160 (single filter 160 a, dual filter 160 b, plunger 160 c and dual filter with shuttle puck 160 d) is to re-use the abrasive used in Abrasive Suspension Jet (ASJ) cutters. Separator system 160 has one input feed line and two output lines. The input feed is dilute slurry from collection system 135. The output lines are derived from the same input fluid to make this a closed-loop abrasive recovery and filtration system for abrasive suspension jet cutting systems. One output line is a concentrated abrasive suspension (a.k.a. slurry) to be reused in the ASJ cutter. The other output feed is an abrasive-free shielding fluid to be reused in the ASJ cutter.

In one embodiment, FIGS. 17 and 18, separation system 160 has a single filter 170 making the separation system a single filter separation system 160 a. Single filter separation system 160 a includes single filter separator (146, 146 a) having a filter housing 158. Single filter separation system 160 a further includes dilute slurry valve 162 for introducing dilute slurry into single filter separator 146 a from collection system 135. Dilute slurry pressure sensor 164 senses dilute slurry pressure coming into separator 146. Within separator 146 is a moveable filter plate 168 having a filter 170. Filter 170 is located between the dilute slurry inlet 192 and reclaimed shielding fluid outlet 194. Filter 170 moves within filter housing 158 between the dilute slurry inlet 192 and the reclaimed shielding fluid outlet 194. Moveable filter plate 168 are designed to be easily removed from the system and replaced with fresh filter plates. Separator agitator 172 mixes the slurry within the separator. Agitator motor 174 drives the agitator. Filter plate linear actuator 176 moves movable filter plate 168 back and forth within separator 146. Reclaimed shielding fluid exits separator 146 through reclaimed shielding fluid valve 178 to shielding fluid boost pump 148. Reclaimed shielding fluid pressure sensor 180 senses pressure of reclaimed shielding fluid exiting single filter separator 146 a. Concentrated slurry exits single separator 146 a through concentrated slurry valve 182. The concentrated slurry enters fluid property controller 152 having fluid property sensor 153 and density logic 155 and/or viscosity logic 157. Fluid property controller 152 monitors density and viscosity of concentrated slurry. Slurry concentrated within filter housing 158 exits the filter housing and is transported to slurry conditioning tank 154.

Operation of separator system 146, 146 a is as follows. With dilute slurry valve 162 and reclaimed shielding fluid valve 178 open and concentrated slurry valve 182 closed, dilute slurry pump 142 transports diluted slurry from catch tank 134 into filter housing 158 and through moveable filter plate 168. Moveable filter plate 168 is connected to filter plate actuation system 159 which allows the filter plate to move linearly within the filter housing. Moveable filter plate 168 includes a mesh or porous material (a.k.a. filter 170) that allows the base fluid to pass through but restricts abrasive. The diluted slurry begins to separate into shielding fluid that passes through the filter, and concentrated slurry that does not flow through the filter.

Pressure transducers (dilute slurry pressure sensor 164 and reclaimed shielding fluid pressure sensor 180) continuously monitor the pressure on both sides of the filter plate. An increasing pressure differential across the filter plate corresponds to the abrasive particles clogging the filter media and reduced filtration throughput. Separator agitator 172, which may be a propeller, is designed to unclog abrasive from the filter plate to reduce this pressure differential as well as to ensure a homogenous mixture of slurry. Further increases in a pressure differential indicate the separator agitator 172 is becoming ineffective. In this situation dilute slurry pump 142 will then stop, dilute slurry valve 162 will close, reclaimed shielding fluid valve 178 will close and the filter plate linear actuator 176 will move moveable filter plate 168 away from the input feed line. This motion creates a higher pressure on the lower side of filter 170 relative to the upper side of the filter 170 that forces fluid through filter 170 in the opposite direction of filtration. Substantially all abrasive trapped in the filter media and the abrasive cake on the surface of the filter is removed during this process. This process is called a “back-purge” and both restores filter throughput and greatly extends the usable filter life. Separator agitator motor 174 will drive separator agitator 172 to uniformly distribute abrasive within the filter housing 158. Dilute slurry valve 162 and reclaimed shielding fluid valve 178 then open; dilute slurry pump 142 turns on, and the filtering process resumes.

Fluid flow meter 195 and fluid property controller 152 monitor and provide feedback to the filtration system. When the slurry in the filter housing matches the desired slurry density, concentrated slurry valve 182 opens, dilute slurry valve 162 closes, and the filter plate linear actuator 176 moves moveable filter plate 168 towards the slurry output line. This discharges the concentrated slurry out of filter housing 158. Once the slurry is discharged, concentrated slurry valve 182 closes, dilute slurry valve 162 opens, moveable filter plate 168 moves back towards its starting position, and dilute slurry pump 142 begins pumping more dilute slurry through the filter plate, restarting the filtration cycle.

Fluid flow meter 195 and fluid property controller 152 provide feedback to reclamation system 100. The density of the dilute slurry being input into filter housing 158 is determined using the following equation:

ρ_(DS)=(ρ_(CS) +R*ρ _(SF))/(1+R)

where R is the volume ratio of shielding fluid to concentrated slurry exiting filter housing 158, ρ_(CS) is the density of concentrated slurry, ρ_(DS) is the density of dilute slurry, and ρ_(SF) is the density of shielding fluid. The density of concentrated slurry in fluid property controller 152 is calculated with density logic 155. The density of the shielding fluid is a known using use the combined mass and volume of the shielding fluid and its additives. The ratio R is determined from the previous filtration cycle by dividing the total volume of shielding fluid exiting filter housing 158 from the total concentrated slurry volume exiting the filter housing. This dilute slurry density value is used to determine the target volume ratio R for the next filtration cycle by rearranging the previous equation to solve for R:

R=(ρ_(CS)−ρ_(DS))/(ρ_(DS)−ρ_(SF))

Measuring the distance that movable filter plate 168 travels while slurry is being discharged from filter housing 158 provides the volume of concentrated slurry exiting the filter housing. Multiplying this volume by R obtained in the equation above, yields a target volume of reclaimed shielding fluid to flow through filter 170 during the next filtration cycle. Fluid flow meter 195, which may be measuring reclaimed shielding fluid output flow from filter housing or dilute slurry input flow to filter housing, records the fluid flow during the filtration cycle. When the targeted volume of shielding fluid has flowed through filter 170, the now concentrated slurry in the filter housing has reached the desired density.

In one embodiment, FIGS. 19 and 20, separation system 160 can have two filters, a first filter 170 a located in stationary filter plate 184 and a second filter 170 b located in moveable filter plate 168, making the separation system a dual filter separation system 160 b. Stationary filter plate 184 is located between the dilute slurry inlet 192 and second shielding fluid outlet 194 b. This additional stationary filter plate 184 provides more filter surface area for increased filtration throughput. Moveable filter plate 168 moves between the dilute slurry inlet 192 and first shielding fluid outlet 194 b. First shielding fluid outlet 194 a and second shielding fluid outlet 194 b are hydrodynamically connected. Operation is the same as described above for the single filter separation system 160 a, but whenever base fluid is flowing through movable filter plate 168, the base fluid is also flowing through stationary filter plate 184.

In one embodiment, FIG. 21, separation system 160 can have two filters and a plunger 186 making the separation system a plunger separation system 160 c. Two stationary filter plates 184 with an additional shielding fluid output line can be fashioned to the dilute slurry input side of filter housing 158. Having two stationary filter plates 184 (top stationary slurry plate 184 a and bottom stationary slurry plate 184 b) provides more filter surface area for increased filtration throughput.

The separator system 160 c includes a filter housing 158 having first dilute slurry inlet 192 a, second dilute slurry inlet 192 b, first stationary filter 170 a, second filter 170 b, plunger 186, first reclaimed shielding fluid outlet 194 a, second reclaimed shielding fluid outlet 194 b, first concentrated slurry outlet 193 a, and second concentrated slurry outlet 193 b. First filter 170 a is located between first dilute slurry inlet 192 a and first reclaimed shielding fluid outlet 194 a. Second filter 170 b is located between second dilute slurry inlet 192 b and second reclaimed shielding fluid outlet 194 b. Plunger 186 is located between first filter 170 a and second filter 170 b.

Operation of plunger separation system 160 c is as follows. With dilute slurry valve 162 a open, dilute slurry valve 162 b closed, concentrated slurry valves 182 a and 182 b closed, reclaimed shielding fluid valve 178 b open, and reclaimed shielding fluid valve 178 a closed, dilute slurry pump 142 transports diluted slurry from catch tank 134 into filter housing 158. Fluid pressure then drives plunger 186 towards the bottom stationary filter plate 184 b. Bottom stationary filter plate 184 b includes a mesh or porous material that allows the base fluid to pass through, but restricts abrasive. The diluted slurry begins to separate into shielding fluid that passes through bottom stationary filter plate 184 b, and concentrated slurry that does not flow through the bottom stationary filter plate. Pressure transducers (dilute slurry pressure sensors 164 a and 164 b, and reclaimed shielding fluid pressure sensor 180) continuously monitor the pressure on both sides of the filter plate. An increasing pressure differential across the filter plate corresponds to the abrasive particles clogging the filter media and reduced filtration throughput. Separator agitator motors 174 a and 174 b drive separator agitators 172 a and 172 b, respectively. Separator agitators 172 a and 172 b, which may be propellers, are designed to unclog abrasive from the filter plate to reduce this pressure differential as well as to ensure a homogenous mixture of slurry.

Fluid flow meter 195 and fluid property controller 152 provide feedback to the filtration system. When the slurry in the bottom part of the filter housing matches the desired slurry density, reclaimed shielding fluid valve 178 b will close, and concentrated slurry valve 182 b will open. Dilute slurry pump 142 will continue to fill the filter housing above plunger 186 with dilute slurry, and the now concentrated slurry will flow out of concentrated slurry valve 182 b, through fluid property controller 152, and to slurry conditioning tank 154.

When the concentrated slurry between bottom stationary filter plate 184 b and plunger 186 is purged out of filter housing 158, concentrated slurry valve 182 b closes, reclaimed shielding fluid valve 178 a opens, reclaimed shielding fluid valve 178 b closes, dilute slurry valve 162 a closes, and dilute slurry valve 162 b opens. Dilute slurry pump 142 then begins to transport dilute slurry through dilute slurry valve 162 b and into filter housing 158 between the plunger and bottom stationary filter 184 b. The fluid pressure drives plunger 186 towards top stationary filter plate 184 a. The diluted slurry in the top part of filter housing 158 that is between the plunger and top stationary filter plate 184 a begins to separate into fluid that passes through the top stationary filter plate, and concentrated slurry that does not flow through the top stationary filter plate.

Fluid flow meter 195 and fluid property controller 152 provide feedback to the filtration system. When the slurry in the top part of filter housing 158 matches the desired slurry density, reclaimed shielding valve 178 a closes, and concentrated slurry valve 182 a opens. Dilute slurry pump 142 will continue to transport dilute slurry into the filter housing between plunger 186 and bottom stationary filter plate 184 b. This action pushes plunger 186 towards top stationary filter plate 184 a, and forces concentrated slurry out of concentrated slurry valve 182 a, through fluid property controller 152, and to slurry conditioning tank 154. When the concentrated slurry between top stationary filter plate 184 a and plunger 186 is purged out of filter housing 158, dilute slurry valve 162 opens, dilute slurry valve 162 b closes, shielding fluid valves 178 a and 178 b open, and concentrated slurry valve 182 a closes. Dilute slurry pump 142 then fills the top part of filter housing 158 between top stationary filter plate 184 a and plunger 186 with dilute slurry, repeating the filtration cycle.

In another embodiment, FIGS. 22-23, separation system 160 can have two filters 170, first filter 170 a located in stationary filter plate 184 and second filter 170 b located in movable filter plate 168, and movable shuttle puck 188 located downstream of movable filter plate 168, making the separation system a dual filter separation system with shuttle puck 160 d. Moveable shuttle puck 188 has a moveable shuttle puck collar 190. Dual filter separation system with shuttle puck 160 d further includes dilute slurry valve 162 for introducing dilute slurry, at dilute slurry inlet 192, into dual filter separation system with shuttle puck 160 d from collection system 135. Dilute slurry pressure sensor 164 senses dilute slurry pressure coming into separator 146 d. Within separator 146 d is a movable filter plate 168 having second filter 170 b, stationary filter plate 184 having first filter 170 a, and movable shuttle puck 188. First filter 170 a does not move and is located hydrodynamically between the dilute slurry inlet 192 and second reclaimed shielding fluid outlet 194 b. Second filter 170 b moves within filter housing 158 between the dilute slurry inlet 192 and the first reclaimed shielding fluid outlet 194 a. Movable shuttle puck 188 is located between the first reclaimed shielding fluid outlet 194 a and the second reclaimed shielding fluid outlet 194 b. Movable shuttle puck 188 can move with movable filter plate 168 when filling filter housing 158 with dilute slurry and when purging the concentrated slurry out of the housing. Movable shuttle puck 188 also moves with movable filter plate 168 when back purging first filter 170 a. Movable shuttle puck 188 moves independently of movable filter plate 168 when back purging second filter 170 b. Movable filter plate 168 and stationary filter plate 184 are designed to be easily removed from the system and replaced with fresh filter plates. Separator agitator 172 mixes the slurry within the separator 146 d. Separator Agitator motor 174 drives the agitator. Filter plate and shuttle puck linear actuator 177 moves movable filter plate 168 and movable shuttle puck 188 back and forth within separator 146 d. Reclaimed shielding fluid exits separator 146 d through reclaimed shielding fluid valves 178 a and 178 b and then in some instances, through fluid flow meter 195 to shielding fluid boost pump 148. Reclaimed shielding fluid pressure sensors 180 a and 180 b sense the pressure of reclaimed shielding fluid exiting dual filter with shuttle puck separator 146 d. Concentrated slurry exits dual filter with shuttle puck separator 146 d through concentrated slurry valve 182. The concentrated slurry enters fluid property controller 152 having fluid property sensor 153 and density logic 155 and/or viscosity logic 157. Fluid property controller 152 monitors density and viscosity of concentrated slurry. Slurry concentrated within filter housing 158 exits the filter housing and is transported to slurry conditioning tank 154.

Operation of separator system 146, 146 d is as follows. With dilute slurry valve 162, reclaimed shielding fluid valves 178 a and 178 b, and reclaimed shielding fluid purge control valves 202 a and 202 b open, and concentrated slurry valve 182 closed, dilute slurry pump 142 transports dilute slurry from catch tank 134 into filter housing 158 and through movable filter plate 168 and stationary filter plate 184. Movable filter plate 168 and stationary filter plate 184 are hydrodynamically connected when reclaimed shielding fluid purge control vales 202 a and 202 b are open. Movable filter plate 168 is connected to filter plate and shuttle puck linear actuator 177 which allows the movable filter plate and shuttle puck to move linearly along the axis of filter housing 158. Movable filter plate 168 and stationary filter plate 184 includes a mesh or porous material (a.k.a filters 170 a and 170 b) that allows the base fluid to pass through but restricts abrasive. The diluted slurry begins to separate into shielding fluid that passes through the filters, and concentrated slurry that does not flow through the filters.

Pressure transducers (dilute slurry pressure sensor 164 and reclaimed shielding fluid pressure sensors 180 a and 180 b) continuously monitor the pressure on both sides of both filter plates. An increasing pressure differential across the individual filter plates corresponds to the abrasive particles clogging the filter media and a reduced filtration throughput. Separator agitator 172 may be a propeller, pump, acoustic vibrator, mechanical vibrator or brushes. Separator agitator 172 is designed to unclog abrasive from the filter plates to reduce this pressure differential as well as to ensure a homogenous mixture of slurry. Further increases in a pressure differential indicate the separator agitator 172 is becoming ineffective. In this situation dilute slurry pump 142 will then stop, dilute slurry valve 162 will close, reclaimed shielding fluid valves 178 a and 178 b will close and the filter plate linear actuator 176 will move movable filter plate 168 and movable shuttle puck 188 away from dilute slurry inlet 192. At first, movable shuttle puck 188 and movable filter plate 168 move together at the same speed. This motion creates a lower pressure on the lower side of stationary filter plate 184 a relative to the upper side of stationary filter plate 184 a that forces fluid through stationary filter plate 184 a in the opposite direction of filtration. When moveable shuttle puck 188 reaches movable shuttle puck backstop 198, the movable shuttle puck no longer moves together with movable filter plate 168. At this time, moveable shuttle puck 188 stops moving, and movable filter plate 168 continues to move downwards as movable shuttle puck back-purge spring 196 begins to compress. This relative motion between movable filter plate 168 and movable shuttle puck 188, changes the volume of fluid between movable filter plate and movable shuttle puck due to fluid being forced through the movable filter plate in the opposite direction of filtration. Substantially all abrasive trapped in both the filter's media and the abrasive cake on the surface of the filters are removed during this process. This process is called a “back-purge” and both restores filter throughput and greatly extends the usable filter life. The movable shuttle puck back-purge spring 196 and movable shuttle puck backstop 198 ensure that both filters 170 a and 170 b can be back-purged independently. Separator agitator 172 mixes the abrasive cake that was removed from the filters to make a homogenous slurry. Dilute slurry valve 162 and reclaimed shielding fluid valves 178 a and 178 b then open; dilute slurry pump 142 turns on, and the filtering process resumes.

Fluid flow meter 195 and fluid property controller 152 provide feedback to the filtration system When the slurry in the filter housing matches the desired slurry density, concentrated slurry valve 182 opens, dilute slurry valve 162 closes, reclaimed shielding fluid valve 178 a closes, reclaimed shielding fluid valve 178 b remains open, and reclaimed shielding fluid purge control valves 202 a and 202 b close. Then the filter plate and shuttle puck linear actuator 177 moves movable filter plate 168 and movable shuttle puck 188 towards concentrated slurry outlet 193. This discharges the concentrated slurry out of filter housing 158. The unchanging volumes of fluid between movable filter plate 168 and movable shuttle puck 188, and between stationary filter plate 184 and reclaimed shielding fluid purge control valves (202 a, 202 b), ensures that no unwarranted filtration occurs as concentrated slurry is being discharged from filter housing 158. Once the slurry is discharged, concentrated slurry valve 182 closes, dilute slurry valve 162 opens, reclaimed shielding fluid purge control valves (202 a, 202 b) open, reclaimed shielding fluid valves 178 a opens, 178 b remains open, and then dilute slurry pump 142 begins pumping more diluted slurry into filter housing 158 as movable filter plate 168 and movable shuttle puck 188 move back towards their original starting positions, restarting the filtration cycle.

In an alternate embodiment abrasive particle and fluid reclamation system 100 can be used with traditional ASJ system that does not use a shielding fluid. Such a reclamation system would include the collection system and recirculation system but may not include a conditioner system or separator.

Fluid and slurry properties may be obtained by monitoring by density and/or viscosity. When the concentrated slurry is not moving through fluid property controller 152, density logic 155 is measuring density. When the concentrated slurry is moving through fluid property controller 152, the viscosity logic is measuring viscosity.

In one embodiment, fluid property sensor 153 may be comprised of a vertical section of pipe, with a pressure transducer near the bottom of the pipe, and another pressure transducer near the top of the pipe. The pipe may be filled with concentrated slurry. In fluid mechanics, the static pressure head equation is:

P ₂ −P ₁ =ρ*g*h

Where P₂=Pressure at the bottom pressure transducer in pascals, P₁=pressure at the top pressure transducer in pascals, ρ=fluid density in kilograms per cubic meter, g=acceleration due to gravity=9.81 meters per squared seconds, and h=distance between pressure transducers in meters. Rearranging this equation to solve for density:

ρ=(P ₂ −P ₁)/(g*h)

Therefore, the density of a fluid can be determined using the known pressure differential of a fluid in a vertical pipe of a known height. Furthermore, the viscosity of a fluid can be determined using a capillary tube. For a Newtonian fluid, viscosity (η) can be characterized by its shear stress (T) divided by rate of shear (γ_(nom)):

η=T/γ _(nom)

Shear stress, T, is expressed as:

T=D*(P ₂ −P ₁)/(4*h)

Where D=diameter of the pipe in meters, and P₂=Pressure at the bottom pressure transducer in pascals, P₁=pressure at the top pressure transducer in pascals, h=distance between pressure transducers in meters. And

γ_(nom)=(32*Q)/(π*D ³)

where Q=volumetric flow rate of the fluid in cubic meters per second, and D=diameter of the pipe in meters. The Weissenberg-Rabinowitsch equation is used to calculate the rate of shear (γ) for a non-Newtonian fluid:

γ=(¼)*γ_(nom)*(3+(d ln(Q)/d ln(T))

where d stands for derivative and In for natural log. Thus, the viscosity of a non-Newtonian fluid can be expressed in its Newtonian form:

η=T/γ

Therefore, by varying Q through a pipe of known D, the viscosity of a non-Newtonian fluid can be determined over multiple rates of shear by also knowing P₁, P₂ and h. Alternatively, shear stress, T, and shear rate, γ, can be determined using the equations above, and can be used to determine the flow consistency index, K, and flow behavior index, n, as described in a fluid model such as the Ostwald-de Waele power law:

T=K*γ ^(n)

Then, the flow consistency index, K, flow behavior index, n, along with shear rate, γ, can be used to solve for viscosity, q:

η=K*γ ^(n-1)

Operation of abrasive suspension jet cutting system 30 includes three general tasks; software programming, cutting and material handling. First, the operator powers on cutting system 30 and through the user interface generates a cutting file that describes the material, thickness and shape or shapes to be cut. Alternatively, a pre-programmed file can be loaded into the system. The operator then lowers the fluid level in the catch tank 134 to expose the material support slats and affixes the material to be cut to platform 52 (a.k.a. slats) with clamping hardware. The cutting head 34 is then aligned to the material to ensure cutting will be performed in the desired location on the material to be cut. The fluid level in the catch tank 134 is then raised to submerge the material to be cut and nozzle 44. All cutting is performed below the fluid surface to ensure no air is entrained in the fluid during operation, which would otherwise complicate the fluid re-use process. The operator then returns to the user interface to start the cutting program. During cutting the electronic controls operate multi-axis motion control system 124 and fluid delivery system 94, including abrasive particle and fluid reclamation system 100, in concert in order to start and stop cutting jet 45 in concert with the prescribed cutting head motion, and to return the reclaimed slurry and shielding fluid to the system. When the cutting is complete the operator lowers the fluid level and removes the finished part or part(s) from the material support slats and unclamps the remaining material to allow material loading for the next cutting program. When all cutting is complete the system is shut down from the user interface and the power is turned off

While several embodiments of the invention, together with modifications thereof, have been described in detail herein and illustrated in the accompanying drawings, it will be evident that various further modifications are possible without departing from the scope of the invention. The scope of the claims should not be limited by the preferred embodiments set forth in the examples, but should be given the broadest interpretation consistent with the description as a whole. 

What is claimed is: 1) A system for abrasive suspension jet cutting using an abrasive slurry and a shielding fluid; comprising: a) a feed assembly having a slurry orifice and a shielding fluid orifice; b) a nozzle; c) an acceleration cavity between the feed assembly and the nozzle; and d) wherein within the acceleration cavity the abrasive slurry and shielding fluid are accelerated together from the slurry orifice to the nozzle while maintaining a shielding fluid barrier substantially unmixed with abrasive slurry around the abrasive slurry, and wherein both the slurry and shielding fluid pass substantially unmixed through the nozzle. 2) The system as recited in claim 1, further comprising only a single pump to commonly energize the abrasive slurry and the shielding fluid to move both through the acceleration cavity and out the nozzle. 3) The system as recited in claim 1, further comprising an abrasive slurry reclamation system. 4) The system as recited in claim 3, wherein the abrasive slurry reclamation system includes a collection system to collect used slurry and shielding fluid, a separator to separate out reusable abrasive particles from used slurry and shielding fluid to produce reclaimed slurry and reclaimed shielding fluid, and a recirculation system to reintroduce the reclaimed slurry and the reclaimed shielding fluid to the feed assembly. 5) The system as recited in claim 4, further including a conditioner system to maintain rheological properties of the base fluid. 6) The system as recited in claim 5, wherein the conditioner system includes a rheological test system and a rheological modifier system. 7) The system as recited in claim 4, further including a fines filter to remove waste particles from shielding fluid. 8) The system as recited in claim 4, further including a fluid reclamation system. 9) The system as recited in claim 1, wherein the nozzle includes a nozzle entrance orifice; wherein the acceleration cavity narrows from the slurry orifice to the nozzle entrance orifice to provide hydrodynamic focusing within the acceleration cavity. 10) The system as recited in claim 9, wherein the acceleration cavity has a taper angle of greater than 15-degrees to minimize mixing within the nozzle. 11) The system as recited in claim 1, wherein the nozzle includes a nozzle length and nozzle orifice diameter; wherein the nozzle length is less than the nozzle orifice diameter. 12) The system as recited in claim 1, further comprising an abrasive wear control system. 13) The system as recited in claim 12, wherein the abrasive wear control system includes a slurry to shielding fluid volume flow regulator and a valve system that allows reverse flow of abrasive slurry through the cutting head to reduce nozzle wear. 14) The system as recited in claim 1, wherein the abrasive slurry has an abrasive slurry volume, wherein the shielding fluid has a shielding fluid volume, wherein the abrasive slurry volume and shielding fluid volume define a total volume, wherein the system provides that the abrasive slurry volume is greater than 30-percent of the total volume as the abrasive slurry exits the nozzle. 15) The system as recited in claim 1, further including the abrasive slurry and the shielding fluid formed from a same base fluid. 16) The system as recited in claim 15, wherein the abrasive slurry and the shielding fluid have matched flow characteristics that is at least one from the group consisting of viscosity and shear rate viscosity dependence. 17) The system as recited in claim 15, wherein the abrasive slurry and the shielding fluid have the same flow modifying additive. 18) The system as recited in claim 17, wherein the flow modifying additive is at least one from the group consisting of a xanthan gum, guar gum, cellulose derivatives, polyacrylamide, gelatin, bentonite, another natural, another synthetic polymer and clay. 19) The system as recited in claim 15, wherein the base fluid consists substantially of water and a suspension agent. 20) A system for abrasive suspension jet cutting using abrasive slurry having abrasive particles contained within a fluid; comprising: a) a cutting head having a nozzle to eject a jet of slurry at high velocity; and b) a reclamation system that collects used abrasive particles and fluid and then returns reclaimed abrasive particles and fluid to the cutting head. 21) The system as recited in claim 20, further comprising a catch tank agitator to mix the used fluid and abrasive particles. 22) The system as recited in claim 20, further comprising a collection system to collect used abrasive particles and fluid. 23) The system as recited in claim 20, further comprising a separator system to separate out reusable abrasive particles from used fluid to produce reclaimed slurry. 24) The system as recited in claim 23, wherein the separator system includes a separator. 25) The system as recited in claim 24, wherein the separator includes a filter housing having a dilute slurry inlet, shielding fluid outlet, a concentrated slurry outlet and a filter, wherein the filter is located between the dilute slurry inlet and shielding fluid outlet. 26) The system as recited in claim 25, wherein the separator further includes a separator agitator. 27) The system as recited in claim 25, wherein the filter moves within the filter housing between the dilute slurry inlet and the shielding fluid outlet. 28) The system as recited in claim 23, wherein the separator system further includes a fluid property controller that monitors at least one from the group consisting of density and viscosity of concentrated slurry. 29) The system as recited in claim 23, wherein the separator system further includes a flow meter. 30) The system as recited in claim 24, wherein the separator includes a filter housing having a dilute slurry inlet, a first shielding fluid outlet, a second shielding fluid outlet, a concentrated slurry outlet, a first filter and a second filter; wherein the first filter is located between the dilute slurry inlet and first shielding fluid outlet, wherein the second filter is moveable between dilute slurry inlet and second shielding fluid outlet. 31) The system as recited in claim 29, wherein the separator further includes a separator agitator. 32) The system as recited in claim 24, wherein the separator system includes a filter housing having a first dilute slurry inlet, a second dilute slurry inlet, a first stationary filter, a second filter, a plunger, a first reclaimed shielding fluid outlet, a second reclaimed shielding fluid outlet, a first concentrated slurry outlet, and a second concentrated slurry outlet; wherein the first filter is located between the first dilute slurry inlet and the first reclaimed shielding fluid outlet; wherein the second filter is located between the second dilute slurry inlet and the second reclaimed shielding fluid outlet; wherein the plunger is located between the first filter and the second filter. 33) The system as recited in claim 24, wherein the separator system further includes a filter housing having a dilute slurry inlet, a first shielding fluid outlet, a second shielding fluid outlet, a concentrated slurry outlet, a stationary filter, a movable filter and movable shuttle puck; wherein the stationary filter is located between the dilute slurry inlet and the second shielding fluid outlet; wherein movable filter is between the dilute slurry inlet and the first shielding fluid outlet; wherein the movable filter and movable shuttle puck can move together to act as plunger and can move independently to back-purge the movable filter. 34) The system as recited in claim 20, further comprising a recirculation system to reintroduce the reclaimed slurry to the cutting head. 35) The system as recited in claim 20, further comprising a conditioner system to maintain rheological properties of the fluid. 36) The system as recited in claim 35, wherein the conditioner system includes a rheological test system. 37) The system as recited in claim 35, wherein the conditioner system includes a biocide system. 38) The system as recited in claim 20, wherein the cutting head ejects a jet of slurry surrounded by shielding fluid. 39) An abrasive wear control system for regulating movement of abrasive slurry and shielding fluid through a suspension jet cutting head, comprising: a) a slurry to shielding fluid volume flow regulator; and b) a valve system that is operable to provide reverse flow of abrasive slurry through the cutting head to reduce nozzle wear. 40) The system as recited in claim 39, wherein the slurry to shielding fluid volume flow regulator includes a slurry pressure regulator and a shielding fluid pressure regulator. 41) The system as recited in claim 39, wherein the slurry to shielding fluid volume flow regulator is a shielding fluid flow control valve. 42) The system as recited in claim 39, where the valve system includes a slurry valve, and a vent valve. 43) The system as recited in claim 39, whereby when starting the suspension jet cutting head, the slurry to shielding fluid volume flow regulator establishes a jet of shielding fluid prior to starting the flow of slurry to the cutting head in order to minimize slurry mixing with the shielding fluid when starting slurry flow. 44) The system as recited in claim 39, whereby when stopping the suspension jet cutting head, the slurry to shielding fluid volume flow regulator stops the flow of slurry to the cutting head, the vent valve is opened temporarily allowing shielding fluid to flow in in reverse from the cutting head and through the slurry valve prior to closing the slurry valve and vent valve in order to minimize nozzle wear during nozzle depressurization. 45) A method for reducing abrasive wear of a suspension jet cutting head nozzle, comprising: a) providing i) a cutting head with a nozzle, ii) a slurry to shielding fluid volume flow regulator, iii) a slurry valve, and iv) a vent valve; b) energizing the shielding fluid and slurry; and c) reversing flow of abrasive slurry through the nozzle while maintaining positive shielding fluid flow during stopping operation to reduce nozzle wear. 46) A method for reducing abrasive wear of a suspension jet cutting head nozzle, comprising: a) providing i) a cutting head with a nozzle, ii) a slurry to shielding fluid volume flow regulator, iii) a slurry valve, and iv) a vent valve; b) energizing the shielding fluid and slurry; and c) starting flow of abrasive slurry only after shielding fluid is flowing through the nozzle. 47) A cutting head for abrasive suspension jet cutting using an abrasive slurry and a shielding fluid; comprising: a) a feed assembly having a slurry orifice and a shielding fluid orifice; b) a nozzle having a nozzle entrance orifice, a nozzle exit orifice and a nozzle orifice length therebetween; c) an acceleration cavity between the slurry orifice and the nozzle entrance orifice, the acceleration cavity narrows from the slurry orifice to the nozzle entrance orifice to provide hydrodynamic focusing within the acceleration cavity; and d) wherein within the acceleration cavity the abrasive slurry and shielding fluid are accelerated together from the slurry orifice to the nozzle entrance orifice while maintaining a shielding fluid barrier substantially unmixed with abrasive slurry around the abrasive slurry, and wherein both the slurry and shielding fluid pass substantially unmixed through the nozzle. 48) The cutting head as recited in claim 47, wherein the nozzle orifice has a nozzle orifice diameter, wherein nozzle length is less than the nozzle orifice diameter. 49) The cutting head as recited in claim 47, the acceleration cavity having a taper angle greater than 15-degrees. 50) A system for abrasive suspension jet cutting; comprising: a) a feed assembly having a slurry orifice and a shielding fluid orifice; b) a nozzle; c) an acceleration cavity between the slurry orifice and the nozzle; d) abrasive slurry and shielding fluid, wherein the abrasive slurry and shielding fluid have the same flow characteristics; and e) wherein within the acceleration cavity the abrasive slurry and shielding fluid are accelerated together from the slurry orifice to the nozzle as both pass through the acceleration cavity and exit the orifice. 51) The system as recited in claim 50, wherein the abrasive slurry and shielding fluid are formed form the same base fluid. 52) The system as recited in claim 50, wherein the shielding fluid has a flow modifying additive to match the flow characteristics of the shielding fluid to the slurry. 53) The system as recited in claim 52, wherein the flow modifying additive is at least one from the group consisting of a Xanthan Gum, Guar Gum, Cellulose derivatives, Polyacrylamide, gelatin, bentonite, another natural, another synthetic polymer and clay. 54) The system as recited in claim 51, wherein the base fluid consists primarily of water and a suspension agent 